The present invention is novel chlorine end-terminated organosiloxanes and a hydrosilylation process for their preparation. The process comprises contacting a chlorine end-terminated (organohydrogen)siloxane and an .alpha.-olefin in the presence of a platinum catalyst, at a temperature of 50.degree. C. to 200.degree. C. The products of this process are chlorine end-terminated organosiloxanes.
The reaction of olefins with SiH containing compounds is well known. For example, Wagner et al., U.S. Pat. No. 2,851,473, issued Sep. 9, 1958. describe the use of platinum deposited on the gamma allotrope of alumina to catalyze the reaction between molecules containing C.dbd.C bonds and SiH containing monomers.
British Patent No. 1,104,206, published Feb. 21, 1968, describes a process where a silicon compound containing at least one silicon-bonded hydrogen atom per molecule and not more than two hydrogen atoms attached to any one silicon atom is reacted with a compound containing aliphatically unsaturated carbon atoms in the presence of a platinum complex. Specific examples of compounds containing aliphatically unsaturated carbon atoms include compounds containing one and two unsaturated bonds.
German Patent Application No. P-2,166,867.7, published Apr. 22, 1976, describes a process where the reaction of trichlorosilane or methyldichlorosilane with a triene is catalyzed with platinum compounds to form bis-silyl olefins. The bis-silyl olefins are further reacted with polymeric unsaturated hydrocarbon chains in the presence of a Lewis acid and a metathesis catalyst to form polymeric hydrocarbons with reactive silyl terminal groups.
Brennan, U.S. Pat. No. 3,440,263, issued Apr. 22, 1969, describes a process in which olefinic compounds containing at least one unsaturated bond are reacted with siloxane polymers containing SiH bonds to form alkylated siloxanes. The siloxane polymers employed by Brennan were end-terminated with hydrogen, hydrocarbyl groups, or alkoxyl groups. Platinum or platinum compounds supported on charcoal were reported as a suitable catalyst for the process.
Getson, U.S. Pat. No. 4,166.078, issued Aug. 28, 1979, describes a process where a modified polyorganosiloxane composition containing in situ generated particulate matter is prepared by reacting an poly(organohydrogen)siloxane with monomers containing aliphatic unsaturated in the presence of free radical initiators. Getson further describes a process where the modified polyorganosiloxane composition is reacted with a compound having at least two vinyl groups per molecule as a cross-linking agent and a catalyst which promotes the addition of SiH groups present in the modified polyorganosiloxane composition to vinyl groups of the cross-linking agent. Platinum is described as a suitable catalyst for the cross-linking process.
The cited art does not recognize that .alpha.-olefins can be hydrosilylated with chlorine end terminated (organohydrogen)siloxanes in the presence of a platinum catalyst without affecting the reactive chlorine substituents. The novel chlorine end-terminated organosiloxanes prepared by this process are compatible in oils and waxes and can be used as additives to improve the glide properties of, for example, textile fibers and sound recording materials. They can also be included internally in polymer materials to improve both the processing and finished properties. The presence of the reactive end-terminal chlorines provides a means by which the siloxanes can be bonded to surfaces to provide durable surface treatments. In addition, the chlorine end-terminated organosiloxanes can be used as intermediates to make block copolymers.